The invention relates to a fiberglass counter-pulling rod formwork-strengthening system and a use method. The fiberglass counter-pulling rod formwork-strengthening system comprises a counter-pulling rod and clamping and tension devices at both ends of the counter-pulling rod which is a high-strength fiberglass rod; the two clamping and tension devices are symmetrically mounted at both ends of the counter-pulling rod; and either clamping and tension device comprises a stretch screw cap, an outer cylinder, a clamping sheet and a strengthening screw cap. The strengthening method comprises the mounting use steps of the strengthening system. The technical scheme of the invention can be used for not only satisfying the requirement for firmly strengthening the formwork, but also ensuring the requirement for favorable appearance of fair-faced concrete.